The overall objectives of our research activities are to provide a description of the neural and photochemical events subserving visual adaptation in the vertebrate retina, and to identify, in both man and animal, the cellular origins of abnormalities affecting the adaptive process. Our initial goal is a better understanding of the etiological factors responsible for night-blinding disorders, and of the functional defects that give rise to anomalies in rod-mediated vision. The approaches to be taken towards attaining these objectives can be considered under three headings: (1) Studies on the physiological processes that are involved in adaptation; e.g., the bleaching and regeneration of rhodopsin, the receptoral and post-receptoral mechanisms that regulate visual sensitivity, and the sequence of synaptic events by which information transfer is effected. (2) Studies of animal "models" exhibiting pathological signs that may prove to be homologous with those found in human night-blinding diseases. Included in this aspect of the program are researches utilizing the perfused eye preparation for detailed analysis of the photochemistry and electrophysiology or relatively discrete focal areas of the retina, and for mapping the retinal distribution of functional loss. (3) Studies on the microenvironment of the retinal neurons with particular reference to the sources of retinal potentials that provide useful diagnostic indicators of retinal abnormalities. This phase of the work includes attempts to assess the role of the K ion-glia interaction in influencing neuronal sensitivity, and in initiating the current that gives rise to the slow PIII and b-wave components of the electroretinogram.